Imaging apparatus, image processing method, and recording medium for recording program thereon

ABSTRACT

An imaging apparatus includes: a setting processor which sets an image area including a tracking shooting object image in a pan-blur shooting as a tracking object image as a tracking image area, with respect to a specific frame image; a searching processor, by respectively setting a scanning area for a plurality of frame images following the frame image used to set the tracking image area, and respectively moving the scanning area on each corresponding frame image of the frame images, and makes a comparison of a characteristic amount of an image between the tracking image area and the scanning area, which respectively obtains a scanning area where the characteristic amount of the image is similar to the image in the tracking image area as a tracking object existing area including the tracking object image, with respect to the frame images; a measuring processor, by dividing a difference between a coordinate of the tracking object existing area obtained with respect to one frame image of the frame images and that obtained with respect to a next one by a certain time interval, which measures a moving speed of the tracking object image on a monitor screen; and a displaying processor which displays a speed display mark corresponding to the moving speed of the tracking object image on the monitor screen.

TECHNICAL FIELD

The present invention relates to an imaging apparatus that is capable ofshooting while tracking a moving photographic subject (so-calledpan-blur shooting), an image processing method, and a recording mediumfor recording a program thereon.

BACKGROUND ART

In a case of shooting while tracking a moving photographic subject, asmethods of controlling a direction of an imaging apparatus so as not tolose the photographic subject from a monitor screen of the imagingapparatus, a method of controlling the direction of the imagingapparatus such that a shooting area in the foreground in a movingdirection of a photographic subject becomes larger than a shooting areain the background in the moving direction of the photographic subject(see Japanese patent application publication number 2006-229322), and amethod of controlling the direction of the imaging apparatus such that aphotographic subject does not disappear from the monitor screen whiletracking the photographic subject (see Japanese patent applicationpublication number

As for a pan-blur shooting, as schematically illustrated in FIG. 1, in acase of shooting a photographic subject which is moving at high speed,when shooting is performed while an imaging apparatus (camera) tracks ina moving direction (for example, a direction of an arrow A) of themoving photographic subject at the same speed as a moving speed of animage O of the moving photographic subject on a monitor screen G, themoving photographic subject is shot clearly, and an image T of aphotographic subject that is a still object existing in a background isflowing (streaked), so that the background is blurred. In an image takenby the pan-blur shooting, a high-speed movement of the photographicsubject is further emphatically expressed.

However, in the pan-blur shooting, it is necessary to have a high skillin order to correspond a tracking speed of a camera to a moving speed ofa photographic subject, and it is difficult for general users to performsuch a shooting, and therefore there are many cases of failure by theusers in the pan-blur shooting.

Japanese patent application publication numbers 2006-229322 and2009-100454 have proposed methods of controlling the direction of theimaging apparatus such that the photographic subject does not disappearfrom the monitor screen G while tracking the photographic subject.However, even if the photographic subject does not disappear from themonitor screen G, if there is a difference of speed between a movingspeed of the photographic subject on the screen and a tracking speed ofa camera, there is a problem such that the image O of the photographicsubject on the monitor screen G relatively moves in the case of thepan-blur shooting, and the image O of the photographic subject isblurred, and therefore a suitable pan-blur shot image is not obtained.

SUMMARY OF THE INVENTION

An objective of the present invention is to provide an imaging apparatuscapable of obtaining a suitable pan-blur shot image when a pan-blurshooting is performed while tracking a moving photographic subject, animage processing method, and a recording medium for recording a programthereon.

In order to achieve the above objective, an embodiment of the presentinvention provides: an imaging apparatus comprising: a setting processorwhich sets an image area including a tracking shooting object image in apan-blur shooting as a tracking object image as a tracking image area,with respect to a specific frame image obtained at a certain timeinterval via a shooting optical system and consecutively displayed on amonitor screen; a searching processor which respectively sets a scanningarea to compare with the tracking image area for a plurality of frameimages following the frame image used to set the tracking image area,and respectively moves the scanning area on each corresponding frameimage of the plurality of frame images, and makes a comparison of acharacteristic amount of an image between the tracking image area andthe scanning area, so that the searching processor respectively obtainsa scanning area where the characteristic amount of the image is similarto the image in the tracking image area as a tracking object existingarea including the tracking object image, with respect to the pluralityof frame images; a measuring processor which divides a differencebetween a coordinate of the tracking object existing area obtained withrespect to one frame image of the plurality of frame images and thatobtained with respect to a next frame image to the one frame image bythe certain time interval, so that the measuring processor measures amoving speed of the tracking object image on the monitor screen; and adisplaying processor which displays a speed display mark correspondingto the moving speed of the tracking object image on the monitor screen.

In order to achieve the above objective, an embodiment of the presentinvention provides: an image processing method comprising: a settingprocessing step which sets an image area including a tracking shootingobject image in a pan-blur shooting as a tracking object image as atracking image area, with respect to a specific frame image obtained ata certain time interval via a shooting optical system and consecutivelydisplayed on a monitor screen; a searching processing step whichrespectively sets a scanning area to compare with the tracking imagearea for a plurality of frame images following the frame image used toset the tracking image area, and respectively moves the scanning area oneach corresponding frame image of the plurality of frame images, andmakes a comparison of a characteristic amount of an image between thetracking image area and the scanning area, so that the searchingprocessing step respectively obtains a scanning area where thecharacteristic amount of the image is similar to the image in thetracking image area as a tracking object existing area including thetracking object image, with respect to the plurality of frame images; ameasuring processing step which divides a difference between acoordinate of the tracking object existing area obtained with respect toone frame image of the plurality of frame images and that obtained withrespect to a next frame image to the one frame image by the certain timeinterval, so that the measuring processing step measures a moving speedof the tracking object image on the monitor screen; and a displayingprocessing step which displays a speed display mark corresponding to themoving speed of the tracking object image on the monitor screen.

In order to achieve the above objective, an embodiment of the presentinvention provides: a computer-readable recording medium for recordingthereon a computer program capable of being executed comprising: asetting processing step which sets an image area including a trackingshooting object image in a pan-blur shooting as a tracking object imageas a tracking image area, with respect to a specific frame imageobtained at a certain time interval via a shooting optical system andconsecutively displayed on a monitor screen; a searching processing stepwhich respectively sets a scanning area to compare with the trackingimage area for a plurality of frame images following the frame imageused to set the tracking image area, and respectively moves the scanningarea on each corresponding frame image of the plurality of frame images,and makes a comparison of a characteristic amount of an image betweenthe tracking image area and the scanning area, so that the searchingprocessing step respectively obtains a scanning area where thecharacteristic amount of the image is similar to the image in thetracking image area as a tracking object existing area including thetracking object image, with respect to the plurality of frame images; ameasuring processing step which divides a difference between acoordinate of the tracking object existing area obtained with respect toone frame image of the plurality of frame images and that obtained withrespect to a next one to the one frame image by the certain timeinterval, so that the measuring processing step measures a moving speedof the tracking object image on the monitor screen; and a displayingprocessing step which displays a speed display mark corresponding to themoving speed of the tracking object image on the monitor screen.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory diagram schematically illustrating an exampleof a case of performing a pan-blur shooting.

FIG. 2 is an external view of a digital camera using the pan-blurshooting according to an embodiment of the present invention.

FIG. 3 is a block diagram illustrating a main constitution of eachprocessor for the pan-blur shooting according to the embodiment of thepresent invention.

FIG. 4 is a schematic diagram illustrating an example of N frame images.

FIG. 5 is a frame image used for an explanation of setting of a trackingimage area.

FIGS. 6A and 6B are schematic diagrams of a frame image illustrating arelationship among the tracking image area, a scanning area, and atracking object existing area, where FIG. 6A is a frame image where thetracking image area has been set, and FIG. 6B is a frame imageillustrating a state where the tracking object existing area is beingsearched by using the scanning area.

FIG. 7 is a diagram illustrating a speed display mark displayed on themonitor screen.

FIG. 8 is a block diagram of the digital camera illustrated in FIG. 2.

FIG. 9 is a flowchart illustrating processing steps of image processingaccording to the embodiment of the present invention.

FIG. 10 is a diagram illustrating a frame image obtained by the pan-blurshooting.

DESCRIPTION OF THE EMBODIMENT

Hereinafter, an imaging apparatus according to an embodiment of thepresent invention will be explained with reference to the drawings.

Firstly, image processing of the imaging apparatus to which the presentinvention is applied will be explained with reference to FIGS. 2 and 3.

FIG. 2 is a perspective diagram of the imaging apparatus to which thepresent invention is applied, and in FIG. 2, reference sign 1 denotes acamera body, and reference sign 2 denotes a lens barrel having ashooting optical system.

In the case of performing the pan-blur shooting, for example, a menuscreen is displayed on a monitor screen G provided on the back of thecamera body 1, a pan-blur shooting mode, and a consecutive shooting forN frame images mode are set.

FIG. 3 is a block diagram illustrating each processor of imageprocessing in the pan-blur shooting mode. In FIG. 3, reference sign 3denotes a setting processor, reference sign 4 denotes a searchingprocessor, reference sign 5 denotes a measuring processor, referencesign 6 denotes a displaying processor, reference sign 7 denotes anauto-shooting processor, and reference sign G denotes a monitor screen.

Frame image data obtained via the shooting optical system is displayedas a frame image on the monitor screen G by the displaying processor 6,and inputted to the setting processor 3.

Here, in the setting processor 3, in the pan-blur shooting mode, asillustrated in FIG. 4, frame image data corresponding to frame images F₀to F_(N) of N frame images is inputted. In FIG. 4, photographic subjectimages T and O of the frame image F₀ have been illustrated as an exampleof a photographic subject image.

The setting processor 3, as illustrated in FIG. 5, sets an image areaincluding a photographic subject image O which is a tracking shootingobject in the pan-blur shooting as a tracking image area Q, based on theframe image data corresponding to the frame image F₀ obtained via theshooting optical system.

When the digital camera is aimed at a photographic subject, aphotographic subject image O corresponding to a moving photographicsubject moves and is displayed on the monitor screen G. In the casewhere the moving photographic subject is taken as a tracking shootingobject in the pan-blur shooting, the photographic subject image O istaken as a tracking object image O′, and the tracking object image O′ istracked.

In the setting processor 3, frame image data corresponding to the frameimages F₀ to F_(N) illustrated in FIG. 4 obtained serially via theshooting optical system is continuously inputted, and in real time, thephotographic subject image O corresponding to the frame images F₀ toF_(N) is continuously displayed for monitoring on the monitor screen Gillustrated in FIGS. 2 and 3.

The following explanation will be explained by using the frame images F₀to F_(N), and the frame images F₀ to F_(N) denote images displayed onthe monitor screen G in real time.

A user sets an image area including the photographic subject image Owhich is the tracking shooting object in the pan-blur shooting from thephotographic subject images T and O in the frame image F₀ displayed onthe monitor screen G as the tracking image area Q.

For example, as for the frame image F₀ illustrated in FIG. 5 (imagedisplayed on the monitor screen G), by touching each point A, B, C, andD (four points) on the monitor screen G by the user, a rectangular framesurrounded by each of the specified points A, B, C, and D is set as thetracking image area Q including the photographic subject image O by thesetting processor 3.

Additionally, for example, on the monitor screen G illustrated in FIG.5, by specifying a point P of the photographic subject image O, arectangular frame in a predetermined size (a rectangular frame in whichthe point P is taken as an intersection point of a diagonal line) can beset by the setting processor 3, and the inside of the rectangular framecan be set as the tracking image area Q including the photographicsubject image O.

Furthermore, in this case, an image area with a large difference ofcontrast can be automatically set as the tracking image area Q by thesetting processor 3.

The photographic subject image O existing in the tracking image area Qillustrated in FIG. 6A is taken as the tracking object image O′.

As illustrated in FIG. 6B, the searching processor 4 sets a scanningarea Q″ to compare with the tracking image area Q for each of the frameimages F₁ to F_(N) chronologically after the frame image F₀, and makes acomparison of a characteristic amount of an image between the trackingimage area Q and the scanning area Q″ of each of the frame images F₁ toF_(N) chronologically after, so that the searching processor 4determines whether the scanning area Q″ is a tracking object existingarea Q′ including the tracking object image O′ or not.

Thus, the searching processor 4 obtains the tracking object existingarea Q′ which is chronologically consecutive.

That is, the searching processor 4 takes the tracking image area Q setin the frame image F₀ as a template, and for example, in a searchingarea S of a next frame image F₁ to the frame image F₀ illustrated inFIG. 6A, by setting a scanning area Q″ in each of the right directionand the down direction in a predetermined order and repeating making acomparison between the characteristic amount of the image existing inthe tracking image area Q and a characteristic amount of an imageexisting in the scanning area Q″, as illustrated in FIG. 6B, thesearching processor 4 determines that the scanning area Q″ in whichsimilarity is highest to the image existing in the tracking image area Qis the tracking object existing area Q′ including the tracking objectimage O′.

In FIG. 6B, each point of a rectangular frame surrounding the scanningarea Q″ corresponding to each point A, B, C, and D of the rectangularframe surrounding the tracking image area Q is marked as A″, B″, C″ andD″, and likewise, each point of a rectangular frame surrounding thetracking object existing area Q′ is marked as A′, B′, C′ and D′.

In this embodiment, the searching area S is an entire area of the frameimage F₁, however it is not limited thereto.

Frame images F₀ to F_(N) (N is a positive integer) are serially obtainedat a time interval Δt, and with respect to each of the frame images F₀to F_(N) serially obtained, the tracking object existing area Q′ isdetermined.

A frame image on which searching is performed is taken as a frame imageF_(i) (i is an integer which satisfies 1≦i≦N).

The measuring processor 5 divides a difference between a coordinate ofthe tracking object existing area Q′ on the monitor screen G obtainedwith respect to a frame image F_(i−1) and a coordinate of the trackingobject existing area Q′ on the monitor screen G obtained with respect toa frame image F₁, that is, a shift of the tracking object existing areaQ′, by an obtaining time interval Δt of frame image, so that themeasuring processor 5 measures a moving speed of the tracking objectimage O′ on the monitor screen G.

The displaying processor 6 performs displaying processing that displaysan arrow as a speed display mark VM corresponding to the moving speed ofthe tracking object image O′ obtained by the above measurement on themonitor screen G illustrated in FIG. 7.

For a calculation of similarity between the photographic subject image Oexisting in the tracking image area Q of the frame image F₀ and an imageexisting in the scanning area Q″ of the frame image F₁, for example, abrightness histogram obtained by each pixel existing in the trackingimage area Q and a brightness histogram obtained by each pixel existingin the scanning area Q″ are used.

For example, the brightness histogram obtained by each pixel in thetracking image area Q is taken as q=[q₁, q₂, . . . , q_(n)]. Each of thesigns q₁, q₂, . . . , q_(n) is the number of pixels where the brightnesslevel is “1”, the number of pixels where the brightness level is “2”, .. . , the number of pixels where the brightness level is “n”,respectively.

And, the brightness histogram obtained by each pixel in the scanningarea Q″ is taken as p=[p₁, p₂, . . . , p_(n)]. Each of the signs p₁, p₂,. . . , p_(n) is the number of pixels where the brightness level is “1”,the number of pixels where the brightness level is “2”, . . . , thenumber of pixels where the brightness level is “n”, respectively.

When obtaining each brightness histogram, to minimize an influence of avariation of an area in the brightness histogram, normalization isperformed on all pixels of each of the tracking image area Q and thescanning area Q″.

Similarity Sim between the tracking image area Q and the scanning areaQ″ is obtained by formula 1 below.

$\begin{matrix}{{Sim} = {\sum\limits_{u = 1}^{n}\;\sqrt{p_{u}*q_{u}}}} & \left\lbrack {{formula}\mspace{14mu} 1} \right\rbrack\end{matrix}$

The scanning area Q″ in which the similarity Sim is maximum is taken asthe tracking object existing area Q′ in the frame image F₁.

The searching processor 4 performs such processing to compare thebrightness histograms and search for the scanning area Q″ in which thesimilarity Sim is maximum on each of the frame images F₁ to F_(N) at thetime interval Δt.

Each time the tracking object existing area Q′ is obtained, with respectto the tracking object existing area Q′ obtained per frame image, themeasuring processor 5 performs the calculation below, to obtain themoving speed of the tracking object image O′ existing in the trackingobject existing area Q′ on the monitor screen G, based on a differencebetween the coordinate of the tracking object existing area Q′ on themonitor screen G obtained from the frame image F_(i−1) and thecoordinate of the tracking object image existing area Q′ on the monitorscreen G obtained from the frame image F_(i), that is, based on theshift of the tracking object existing area Q′.

For example, the following formulas 2 and 3 are used for the abovecalculation.

$\begin{matrix}{V_{x} = \frac{x^{\prime} - x}{\Delta\; t}} & \left\lbrack {{formula}\mspace{14mu} 2} \right\rbrack \\{V_{y} = \frac{y^{\prime} - y}{\Delta\; t}} & \left\lbrack {{formula}\mspace{14mu} 3} \right\rbrack\end{matrix}$

Here, V_(x) is a speed in the horizontal direction on the monitor screenG, and V_(y) is a speed in the vertical direction on the monitor screenG. Each of a coordinate (x′, y′) and a coordinate (x, y) is each of acoordinate on the frame image F₀ and a coordinate on the frame image F₁,which specifies a position of the tracking object existing area Q′ onthe monitor screen G. Δt is an obtaining time interval of frame image.

Generally, the moving speed of the tracking object image O′ on themonitor screen G is a value of a difference between the coordinate ofthe tracking object existing area Q′ on the monitor screen G in theframe image F, and the coordinate of the tracking object existing areaQ′ on the monitor screen G in the frame image. F_(i−1), that is, theshift of the tracking object existing area Q′ is divided by theobtaining time interval Δt.

Based on the moving speed obtained by the measuring processor 5, thedisplaying processor 6 displays the arrow as the speed display mark VMon the monitor screen G as illustrated in FIG. 7. The speed display markVM indicates that the longer a length of the arrow, the faster themoving speed of the tracking object image O′ on the monitor screen G.That is, the moving speed of the tracking shooting object in thepan-blur shooting is fast.

The user moves the camera corresponding to a movement of thephotographic subject so as to make the length of the arrow shorter, andthereby it is possible to track the photographic subject and perform asuitable pan-blur shooting.

The auto-shooting processor 7 determines a measurement result of themeasuring processor 5. And when the moving speed of the tracking objectexisting area Q′ on the monitor screen G, that is, the moving speed ofthe tracking object image O′ becomes less than or equal to apredetermined threshold value, shooting is automatically executed, and apan-blur shot image is obtained.

Hereinafter, a hardware constitution of a digital camera as an exampleof an imaging apparatus having those processors will be explained.

FIG. 8 is a block diagram illustrating the hardware constitution of thedigital camera. The digital camera includes a shooting optical system11, a mechanical shutter 12, a CCD (Charge-Coupled Device) 13, a CDS(Correlated Double Sampling) circuit 14, an A/D (Analog-Digital)converter 15, an image processor (image processing circuit) 16, a liquidcrystal display (LCD) 17 having the monitor screen G, a CPU (CentralProcessing Unit) 18, a RAM (Random Access Memory) 19, a ROM (Read-OnlyMemory) 20, a SDRAM (Synchronous Dynamic Random Access Memory) 21, acompressing/decompressing section 22, a memory card 23, an operatingsection 24, a timing signal generator 25, and a motor 26.

Between the shooting optical system 11 and the CCD 13, the mechanicalshutter 12 is disposed, and is used for blocking light from aphotographic subject incident on the CCD 13. A focus lens and the likeof the shooting optical system 11 and the mechanical shutter 12 aredriven by the motor 26.

When the digital camera is aimed at a photographic subject, light fromthe photographic subject is inputted on the CCD 13 through the shootingoptical system 11.

The CCD 13 converts image information of the light inputted through theoptical system 11 to an analog image signal and outputs it. From theimage signal outputted from the CCD 13, a noise component is removed bythe CDS circuit 14, and then the A/D converter 15 converts to a digitalsignal, and the digital signal is inputted to the image processor 16.

The image processor 16 generates image data per image frame from theinputted digital signal. And the generated image data per image frame istemporarily stored in the SDRAM 21, and the image processor 16 performsvarious image processings such as YCrCb converting processing, whitebalance controlling processing, contrast compensating processing, edgeenhancing processing, color converting processing, and the like on thestored image data.

In the white balance controlling processing, color depth of an image isadjusted, and in the contrast compensating processing, contrast of animage is adjusted. In the edge enhancing processing, sharpness of animage is adjusted, and in the color converting processing, color of animage is adjusted. Image data on which signal processing and imageprocessing have been performed is displayed on the monitor screen G ofthe LCD 17 by the image processor 16.

The image data on which the signal processing and image processing havebeen performed is recorded via the compressing/decompressing section 22on the memory card 23. In accordance with an instruction obtained fromthe operating section 24, the compressing/decompressing section 22compresses the image data outputted from the image processor 16 andoutputs it to the memory card 23, and decompresses the image data readfrom the memory card 23 and outputs it to the image processor 16.

Each timing of the CCD 13, the CDS circuit 14, and the A/D converter 15is controlled by the CPU 18 via the timing signal generator 25, whichgenerates a timing signal. The image processor 16, thecompressing/decompressing section 22, and the memory card 23 arecontrolled overall by the CPU 18.

The CPU 18, the ROM 20, which is a read-only memory and in which theprograms and the like are stored, and the RAM 19, which is a freelyreadable and writable memory having a work area used in the variousprocessings, a storage area for various data, and the like, areconnected to each other by a bus line. And the CPU 18 performs variousarithmetic processings in accordance with programs.

An image processing program executed by this digital camera is a moduleconstitution including a function of tracking a photographic subject andmeasuring a moving speed of the photographic subject on the monitorscreen G.

In a case of executing the above image processing program, the CPU 18loads the program in which processing steps of each of the processorsillustrated in FIG. 3 have been written from the ROM 20 as a recordingmedium, and based on the program, executes calculation of the speed ofthe tracking object image O′, executes controlling of display of themonitor screen G of the digital camera, performs image shooting andimage processing, compresses images, and generates a pan-blur shot imagedata in the memory card 23.

Hereinafter, execution of the pan-blur shooting will be explained withreference to a flowchart illustrated in FIG. 9.

An image including a photographic subject image O which is moving isinputted to the image processor 16, and displayed on the monitor screenG of the LCD 17.

For example, when a user touches the monitor screen G while looking atthe monitor screen G, a coordinate of a position on the monitor screen Gwhere the user touched is inputted, and a tracking image area Qincluding the photographic subject image O which is a tracking shootingobject in the pan-blur shooting is set (step S.1).

The CPU 18 firstly functions as the setting processor 3, and selects ahigh contrast area in the tracking image area Q in accordance with atracking program, and sets the tracking image area Q as a trackingobject existing area Q′ including a tracking object image O′.

And then, a characteristic amount of an image in the tracking image areaQ is calculated (step S.2).

The CPU 18 obtains a frame image corresponding to a frame image beingdisplayed as a moving image in real time on the monitor screen G at atime interval Δt, and stores data of consecutive two frame images in theSDRAM 21.

The stored two frame images are taken as a frame image F_(i) and a frameimage F_(i−1), and the CPU 18 uses those frame image data of the frameimage F_(i) and frame image data of the frame image F_(i−1) for trackingprocessing.

Next, the CPU 18 functions as the searching processor 4, and sets ascanning area Q″ for each of frame images F₁ to F_(N) following a frameimage F₀, and changes a position of the scanning area Q″ in a searchingarea S, and executes searching for the tracking object existing area Q′(step S.3).

Each time the position of the scanning area Q″ is changed, the CPU 18calculates a characteristic amount of an image in the scanning area Q″(step S.4). And the CPU 18 executes a calculation of similarity betweenthe characteristic amount of the image in the scanning area Q″ and acharacteristic amount of an image in the tracking image area Q (stepS.5), and makes a comparison between the image in the scanning area Q″and the image in the tracking image area Q (step S.6). And until thesearching in the searching area S is finished (step S.7), the CPU 18performs searching processing of the steps S.3 to S.7, and if there isthe scanning area Q″ where the similarity is highest, the CPU 18determines that it is the tracking object existing area Q′ (step S.8).

Next, with respect to a frame image F_(i) on which the searching isbeing performed, the CPU 18 determines whether the tracking objectexisting area Q′ is obtained or not (step S.9). When the tracking objectexisting area Q′ is not obtained with respect to the frame image F_(i),the CPU 18 determines whether the frame image F_(i) is the Nth frameimage or not (step S.10). And in the case where it is not the Nth frameimage, the processing returns to the step S.3, and the CPU 18 performsthe searching processing on a frame image F_(i+1) where the searching isyet to be performed.

In the step S.10, in the case where it is the Nth frame image, executionof the pan-blur shooting mode is stopped, and it is returned to a normalshooting mode.

With respect to the frame image F, on which the searching is beingperformed, in the case where the tracking object existing area Q′ isobtained, the CPU 18 functions as the measuring processor 5, andcalculates a moving speed of the tracking object image O′ on the monitorscreen G based on frame image data of the tracking object existing areaQ′ obtained with respect to the frame image F_(i−1) and frame image dataof the tracking object existing area Q′ obtained with respect to theframe image F, (step S.11).

The CPU 18 outputs display data based on a result of the moving speed onthe LCD 17. Thus, on the monitor screen G, with the tracking objectexisting area Q′, a speed display mark VM corresponding to the movingspeed of the tracking object image O′ on the monitor screen G isdisplayed (step S.12).

The user, in accordance with an arrow of the speed display mark VM,moves the camera body 1 in the direction where the arrow indicates. If alength of the arrow becomes shorter, a moving speed of the camera body 1becomes closer to the moving speed of the tracking object image O′, andthus, it is possible for the user to recognize that the moving speed ofthe camera body 1 becomes closer to a moving speed of the photographicsubject.

The CPU 18 determines whether the moving speed of the tracking objectimage O′ in the tracking object existing area Q′ on the monitor screen Gis less than or equal to a predetermined threshold value (step S.13),and in a case where the moving speed is less than or equal to thepredetermined threshold value, the shooting is automatically performed(step S.14). Accordingly, a suitable pan-blur shot image is obtained.And then, it is returned to the normal shooting mode.

In the case where the moving speed of the tracking object image O′ inthe tracking object existing area Q′ on the monitor screen G is not lessthan or equal to the predetermined threshold value, the processingreturns to the step S.3, and the CPU 18 repeatedly performs processingafter the step S.3, and when the processing is finished with respect tothe N frame images, the CPU 18 stops the pan-blur shooting, and it isreturned to the normal shooting mode.

In the pan-blur shooting, one pan-blur shot image can be taken in asingle shooting mode, and a plurality of pan-blur shot images can betaken in a consecutive shooting mode.

On image data obtained by the above pan-blur shooting, the signalprocessing and the image processing are performed, and thenpredetermined processing by the compressing/decompressing section 22 areperformed, and it is recorded in the memory card 23.

For example, in the consecutive shooting mode, as illustrated in FIG.10, when the length of the arrow of the speed display mark VM becomesless than or equal to a predetermined threshold value, a shutter isreleased, and the consecutive shooting is performed. And when the lengthof the arrow of the speed display mark VM becomes equal to or more thanthe predetermined threshold value, the consecutive shooting is stopped.Thus, a plurality of a series of pan-blur shot images are obtained. Theuser can choose a suitable pan-blur shot image of the plurality of theseries of pan-blur shot images. Accordingly, it is possible for the userto reliably obtain a suitable pan-blur shot image.

In the case where the moving speed of the tracking object image O′ ofthe tracking object existing area Q′ becomes less than or equal to thepredetermined threshold value, the pan-blur shooting can be performedsuch that an exposure time is set longer than an exposure time obtainedby a light metering calculation and the shutter of the camera isreleased.

And accordingly, it is possible to greatly enhance an effect of thepan-blur shot image. The longer the exposure time becomes, the more ablurring effect that an object image existing in the background flows isenhanced.

Furthermore, if the moving speed of the tracking object existing area Q′becomes less than or equal to the predetermined threshold value, aconsecutive pan-blur shooting can be executed while changing an exposuretime of each frame image data between a shorter exposure time than theexposure time obtained by the light metering calculation and a longerexposure time.

When the above-described consecutive pan-blur shooting is executed, aplurality of pan-blur shot images having different effects are obtained,while changing the exposure time with respect to each of the frameimages F₁ to F_(N).

The longer the exposure time of a series of pan-blur shot images takenconsecutively is, the more the blurring effect that the background flowsis enhanced

According to an embodiment of the present invention, since shooting isautomatically performed when a moving speed of a tracking object imageobtained by a measuring processer is less than or equal to apredetermined threshold value, it is possible to reliably perform apan-blur shooting.

Moreover, in this case, a plurality of pan-blur shot images areconsecutively taken, therefore it is possible to choose a desired shotimage of pan-blur shot images later on.

Furthermore, since a shooting exposure time is set long and shooting isperformed, it is possible to enhance a shooting effect of a pan-blurshot image.

According to an embodiment of the present invention, since a pluralityof pan-blur shooting shot images are consecutively obtained whilechanging a shooting exposure time, it is possible to obtain a pluralityof pan-blurring shot images having different shooting effects at a time.

In a case where a brightness histogram obtained with respect to eacharea is used as a characteristic amount of an image, it is possible touse an existing image processing technique on the brightness histogram.

According to an embodiment of the present invention, it is possible toeasily and reliably perform a pan-blur shooting, even though a user isnot a professional photographer with a high shooting skill.

Although the present invention has been described in terms of exemplaryembodiments, it is not limited hereto. It should be appreciated thatvariations may be made in the embodiments described by persons skilledin the art without departing from the scope of the present invention asdefined by the following claims.

CROSS REFERENCE TO RELATED APPLICATION

The present application is based on and claims priority from Japanesepatent application number 2010-111748, filed May 14, 2010, thedisclosure of which is hereby incorporated by reference herein itsentirety.

The invention claimed is:
 1. An imaging apparatus comprising: a settingprocessor which sets an image area including a tracking shooting objectimage in a pan-blur shooting as a tracking object image as a trackingimage area, with respect to a specific frame image obtained at a certaintime interval via a shooting optical system and consecutively displayedon a monitor screen; a searching processor which respectively sets ascanning area to compare with the tracking image area for a plurality offrame images following the frame image used to set the tracking imagearea, and respectively moves the scanning area on each correspondingframe image of the plurality of frame images, and makes a comparison ofa characteristic amount of an image between the tracking image area andthe scanning area, so that the searching processor respectively obtainsa scanning area where the characteristic amount of the image is similarto the image in the tracking image area as a tracking object existingarea including the tracking object image, with respect to the pluralityof frame images; a measuring processor which divides a differencebetween a coordinate of the tracking object existing area obtained withrespect to one frame image of the plurality of frame images and thatobtained with respect to a next frame image to the one frame image bythe certain time interval, so that the measuring processor measures amoving speed of the tracking object image on the monitor screen; and adisplaying processor which displays a speed display mark correspondingto the moving speed of the tracking object image on the monitor screen.2. The imaging apparatus according to claim 1, comprising anauto-shooting processor which automatically executes shooting when themoving speed of the tracking object image obtained by the measuringprocessor is less than or equal to a predetermined threshold value. 3.The imaging apparatus according to claim 2, wherein the auto-shootingprocessor obtains a plurality of pan-blur shot images by consecutiveshooting.
 4. The imaging apparatus according to claim 2, wherein theauto-shooting processor sets an exposure time when shooting longer thanan appropriate exposure time and executes shooting when the moving speedof the tracking object image is less than or equal to the predeterminedthreshold value.
 5. The imaging apparatus according to claim 3, whereinthe auto-shooting processor obtains the plurality of pan-blur shotimages by consecutive shooting while changing a shooting exposure time.6. The imaging apparatus according to claim 1, wherein thecharacteristic amount of the image is a brightness histogram obtained byeach pixel in each area.
 7. An image processing method comprising: asetting processing step which sets an image area including a trackingshooting object image in a pan-blur shooting as a tracking object imageas a tracking image area, with respect to a specific frame imageobtained at a certain time interval via a shooting optical system andconsecutively displayed on a monitor screen; a searching processing stepwhich respectively sets a scanning area to compare with the trackingimage area for a plurality of frame images following the frame imageused to set the tracking image area, and respectively moves the scanningarea on each corresponding frame image of the plurality of frame images,and makes a comparison of a characteristic amount of an image betweenthe tracking image area and the scanning area, so that the searchingprocessing step respectively obtains a scanning area where thecharacteristic amount of the image is similar to the image in thetracking image area as a tracking object existing area including thetracking object image, with respect to the plurality of frame images; ameasuring processing step which divides a difference between acoordinate of the tracking object existing area obtained with respect toone frame image of the plurality of frame images and that obtained withrespect to a next frame image to the one frame image by the certain timeinterval, so that the measuring processing step measures a moving speedof the tracking object image on the monitor screen; and a displayingprocessing step which displays a speed display mark corresponding to themoving speed of the tracking object image on the monitor screen.
 8. Theimage processing method according to claim 7, comprising anauto-shooting processing step which automatically executes shooting whenthe moving speed of the tracking object image obtained by the measuringprocessing step is less than or equal to a predetermined thresholdvalue.
 9. The image processing method according to claim 8, wherein theauto-shooting processing step obtains a plurality of pan-blur shotimages by consecutive shooting.
 10. The image processing methodaccording to claim 8, wherein the auto-shooting processing step sets anexposure time when shooting longer than an appropriate exposure time andexecutes shooting when the moving speed of the tracking object image isless than or equal to the predetermined threshold value.
 11. The imageprocessing method according to claim 9, wherein the auto-shootingprocessing step obtains the plurality of pan-blur shot images byconsecutive shooting while changing a shooting exposure time.
 12. Acomputer-readable recording medium for recording thereon a computerprogram capable of being executed comprising: a setting processing stepwhich sets an image area including a tracking shooting object image in apan-blur shooting as a tracking object image as a tracking image area,with respect to a specific frame image obtained at a certain timeinterval via a shooting optical system and consecutively displayed on amonitor screen; a searching processing step which respectively sets ascanning area to compare with the tracking image area for a plurality offrame images following the frame image used to set the tracking imagearea, and respectively moves the scanning area on each correspondingframe image of the plurality of frame images, and makes a comparison ofa characteristic amount of an image between the tracking image area andthe scanning area, so that the searching processing step respectivelyobtains a scanning area where the characteristic amount of the image issimilar to the image in the tracking image area as a tracking objectexisting area including the tracking object image, with respect to theplurality of frame images; a measuring processing step which divides adifference between a coordinate of the tracking object existing areaobtained with respect to one frame image of the plurality of frameimages and that obtained with respect to a next one to the one frameimage by the certain time interval, so that the measuring processingstep measures a moving speed of the tracking object image on the monitorscreen; and a displaying processing step which displays a speed displaymark corresponding to the moving speed of the tracking object image onthe monitor screen.